1. Field of the Invention
The present invention generally relates to a sealing apparatus for rotating shafts, in particular a stern tube seal for a propeller shaft of a ship, with or without shaft bushings, with aligned gaskets resting on the shaft and located in a stationary support system, preferably of an axial face seal, and with a backup seal located in the support system, which is designed as a gland seal with soft packings, and a gland which can be moved in the axial direction in a guide body connected to the support system, whereby between the guide body and the gland there is a cavity system into which, when there is a failure of the main seal, a hydraulic or pneumatic pressure medium can be introduced which activates the backup seal.
2. Background Information
In seals of the type described above, such as that disclosed by Federal Republic of Germany Published Patent Application No. P 40 28 048.9, the cavity system essentially consists of a single, ring-shaped inflatable body, which is inserted flush into an annular space between the guide body and the gland. German Published Patent Application No. P 40 28 048.9 corresponds to currently pending U.S. patent application Ser. No. 07/755,001, filed Sep. 5, 1991 now U.S. Pat. No. 5,209,497 from which the present application claims continuation-in-part status.
On such seals, there is generally a risk of the failure of the entire backup seal in the event of a leak in the single pressure body.